Devil's Son-in-Law - Chapter 1215: The Day The World Changed

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

An editor at the prime of her life—and with maybe just a little too much free time—finds herself waking up in one of her favorite RPGs with no clue as to what's going on or how to get back home.This might be the part where others rejoice over getting whisked away to a world of wizards and magic, but she certainly doesn't think it's anything to celebrate about.After all, she woke up in the body of a small-time villain with some severe personality issues.

Suddenly, the mysterious book I received turned out to describe my own life?Once I chose to change my destiny, the life within the book changed as well.In the book, I encountered insincerity, spent ten years behind bars, and witnessed viruses laying Siege...Cancer, bus plunging off cliffs, plane crashes, senile dementia ... even the end of days – a variety of deaths; was this fate's punishment for the rebels?No one is a hero; it is just that this disaster-ridden fate forcibly made me into a warrior charging into battle.Those who killed me over and over will ultimately make me stronger!Through numerous life simulations, I amassed wealth from the financial markets, rescued innocent girls from felons, and acquired advanced technology from the future...Although I always encounter various disasters and accidents, I still strive to flutter the butterfly's wings, changing my original fate little by little.After countless simulations, the world too embarked on a completely different path.However, where did this autobiography come from?Behind it all, what kind of unknown conspiracy is lurking...[A literary man's laid-back daily life of unlimited simulations to save the world]

After announcing it will be discontinuing all service, the internet game ‘Yggdrasil’ shut down… That was the plan, but for some reason, the player character did not log out some time after the server was closed. NPCs start to become sentient. A normal youth who loves gaming in the real world seemed to have been transported into an alternate world along with his guild, becoming the strongest mage with the appearance of a skeleton, Momonga. He leads his guild ‘Ainz Ooal Gown’ towards an unprecedented legendary fantasy adventure!